#!/usr/bin/perl -w
#
# file: sas-monitoring
# purpose: monitor sas web servers

use strict;

use Data::Dumper;
use IO::Socket;

my @WEB_SERVERS = qw(
10.3.7.105
10.3.7.106
10.3.7.107
10.3.7.108
10.3.7.109
10.3.7.62
10.3.7.63
10.3.7.78
10.3.7.79
10.3.7.60
10.3.7.61
);

my $TIMEOUT_SECONDS = 1;
my $SERVER_PORT     = 80;

# -- main --

my %connection_stats; # for tracking connection success/failure counts
for (@WEB_SERVERS) {
	$connection_stats{$_} = {};
	$connection_stats{$_}{success} = 0;
	$connection_stats{$_}{failure} = 0;
}

# GOAL : give the user a way to read connect stats via the USR1 signal.
# DOC : this signal will interrupt the socket connect call and count as a
#       failure
$SIG{'USR1'} = sub {

	my @ip_list = keys %connection_stats;

	@ip_list = sort
		{ $connection_stats{$b}{failure} <=> $connection_stats{$a}{failure} }
		@ip_list;

	print "\n";
	for my $i (@ip_list) {
		print sprintf("%16s", $i), ": failures: ",
			$connection_stats{$i}{failure}, " successes: ",
			$connection_stats{$i}{success}, "\n";
	}
};
print $0 ," is starting as pid ", $$ ,
	".  From another window you may run:\n  kill -USR1 ", $$, "\n";

while (1) {
	# GOAL : try to connect to the server
	SERVER: for my $server_ip (@WEB_SERVERS) {
		  my $sock = new IO::Socket::INET (
                                 PeerAddr => $server_ip,
                                 PeerPort => $SERVER_PORT,
                                 Proto    => 'tcp',
								 Timeout  => $TIMEOUT_SECONDS,
							 );
		  unless ($sock) {
			  warn "Could not create socket to $server_ip : $!\n";
			  $connection_stats{$server_ip}{failure} ++;
			  next SERVER;
		  }
		  $connection_stats{$server_ip}{success} ++;
		  close($sock);
		  syswrite(STDOUT, '.', 1);
	  }

	  # wait a second then check again
	  #syswrite(STDOUT, "\n", 1);
	  sleep(1);
}